Absence of self-reported neuropsychiatric and somatic symptoms after Omicron variant SARS-CoV-2 breakthrough infections.

Persistent somatic and neuropsychiatric symptoms have been frequently described in patients after infection with severe acute respiratory syndrome coronavirus 2 even after a benign clinical course of the acute infection during the early phases of the coronavirus severe acute respiratory syndrome coronavirus 2 pandemic and are part of Long COVID. The Omicron variant emerged in November 2021 and has rapidly become predominant due to its high infectivity and suboptimal vaccine cross-protection. The frequency of neuropsychiatric post-acute sequelae after infection with the severe acute respiratory syndrome coronavirus 2 Omicron and adequate vaccination status is not known. Here, we aimed to characterize post-acute symptoms in individuals with asymptomatic or mildly symptomatic breakthrough infection with severe acute respiratory syndrome coronavirus 2. These individuals had either proven infection with the Omicron variant (n = 157) or their infection occurred in 2022 where Omicron was the predominant variant of severe acute respiratory syndrome coronavirus 2 in Germany (n = 107). This monocentric cross-sectional study was conducted at the University Medical Center Hamburg-Eppendorf between 11 February 2022 and 11 April 2022. We employed questionnaires addressing self-reported somatic symptom burden (Somatic Symptom Scale 8) and neuropsychiatric symptoms including mood (Patient Health Questionnaire 2), anxiety (Generalized Anxiety Disorder 7), attention (Mindful Attention Awareness Scale) and fatigue (Fatigue Assessment Scale) in a cohort of hospital workers. Scores were compared between 175 individuals less than 4 weeks after positive testing for severe acute respiratory syndrome coronavirus 2, 88 individuals more than 4 weeks after positive testing and 87 severe acute respiratory syndrome coronavirus 2 uninfected controls. The majority (n = 313; 89.5%) of included individuals were vaccinated at least three times. After recovery from infection, no significant differences in scores assessing neuropsychiatric and somatic symptoms were detected between the three groups (severe acute respiratory syndrome coronavirus 2 uninfected controls, individuals less and more than 4 weeks after positive testing) independent of age, sex, preconditions and vaccination status. In addition, self-reported symptom burden did not significantly correlate with the number of vaccinations against severe acute respiratory syndrome coronavirus 2, time from recovery or the number of infections. Notably, in all three groups, the mean scores for each item of our questionnaire lay below the pathological threshold. Our data show that persistent neuropsychiatric and somatic symptoms after recovery from severe acute respiratory syndrome coronavirus 2 infection in fully vaccinated hospital workers do not occur more frequently than that in uninfected individuals. This will guide healthcare professionals in the clinical management of patients after recovery from breakthrough infections with severe acute respiratory syndrome coronavirus 2.

Therapeutic Management of COVID-19 in a Pediatric Patient with Neurodegenerative CLN2 Disease and ICV-Enzyme Replacement Therapy: A Case Report.

The 12 years old male patient presented here suffers from neuronal ceroid lipofuscinoses 2 (CLN2) (MIM# 204500) and receives intracerebroventricular enzyme replacement therapy (ICV-ERT) every 14 days. After the emergence of the coronavirus disease 2019 (COVID-19) pandemic, routine care of children and adolescents with rare chronic diseases has become challenging. Although, in general, children do not develop severe COVID-19, when severe acute respiratory syndrome coronavirus 2 infection was detected by polymerase chain reaction-screening examination in our CLN2 patient before hospital admission for ICV-ERT, he was regarded to be at risk. Upon diagnosis, the patient developed respiratory deterioration symptoms and was admitted to our pediatric intensive care unit to receive oxygen, remdesivir, and steroids. As far as we know, this is the first CLN2 patient receiving intraventricular enzyme therapy with COVID-19 who required intensive care treatment and specific therapy.

Clinical performance and accuracy of a qPCR-based SARS-CoV-2 mass-screening workflow for healthcare-worker surveillance using pooled self-sampled gargling solutions: A cross-sectional study.

INTRODUCTION: The large number of asymptomatic SARS-CoV-2 infections necessitates general screening of employees. We evaluate the performance of a SARS-CoV-2 screening program in asymptomatic healthcare-workers (HCW), utilizing self-sampled gargling-solution and sample pooling for RT-qPCR. METHODS: We conducted a cross-sectional retrospective study to collect real-life data on the performance of a screening-workflow based on automated-pooling and high-throughput qPCR testing over a 3-month-period at the University Hospital Hamburg. RESULTS: Matrix validation reveals that lower limit of detection for SARS-CoV-2 RNA in gargling-solution was 180 copies/mL (5-sample-pool). A total of 55,122 self-collected gargle samples (= 7513 HCWs) was analyzed. The median time to result was 8.5 hours (IQR 7.2-10.8). Of 11,192 pools analyzed, 11,041 (98.7%) were negative, 69 (0.6%) were positive and 82 (0.7%) were invalid. Individual testing of pool participants revealed 57 SARS-CoV-2 previously unrecognized infections. All 57 HCWs were either pre-symptomatic or asymptomatic (prevalence 0.76%,CI95%0.58-0.98%). Accuracy based on HCWs with gargle-solution and NP-swab available within 3-day-interval (N = 521) was 99.5% (CI95%98.3-99.9%), sensitivity 88.9% (CI95%65.3-98.6%) while specificity 99.8% (CI95%98.9-99.9). CONCLUSION: This workflow was highly effective in identifying SARS-CoV-2 positive HCWs, thereby lowering the potential of inter-HCW and HCW-patient transmissions. Automated-sample-pooling helped to conserve qPCR reagents and represents a promising alternative strategy to antigen testing in mass-screening programs.

[Mild COVID-19 disease in healthcare workers at a German university clinic : The "first wave" at the University Medical Center Hamburg-Eppendorf]. / Milde COVID-19-Verläufe bei Mitarbeitenden einer Universitätsklinik : Die "erste Welle" am Universitätsklinikum Hamburg-Eppendorf.

BACKGROUND: Healthcare workers are among the most exposed and potentially most threatened populations of the ongoing COVID-19 pandemic. Despite some reports on numbers of infections with SARS-CoV­2 in German healthcare workers, the courses of their clinical presentation when affected by COVID-19 are not well described. OBJECTIVE: In this contribution, characteristics and progressions of infected cases among healthcare workers at the University Medical Center Hamburg-Eppendorf during the first wave of the COVID-19 pandemic will be presented. METHODS: Between 1 July and 28 July 2020, 67 healthcare workers, who previously tested positive for SARS-CoV­2 via PCR, were invited via E­mail to participate in an anonymous online questionnaire; 39 persons participated. RESULTS: Participants (58%) were mostly ≤ 39 years old (64%) and female (70%). Most healthcare workers were involved in direct patient management (85%), including contact with SARS-CoV­2 positive patients (62%). All participants reported acute symptoms with a median duration of 19 days. The most frequent symptoms were fatigue (85%), anosmia (67%), cough (64%), headache (62%), and shortness of breath (51%). The disease course was mostly mild with low admission rates (5%). Ongoing symptoms lasting more than four weeks post-symptom-onset, particularly anosmia, fatigue, and shortness of breath, were reported by 38%. This group more frequently had pre-existing conditions (53% vs. 12%, p = 0.010), specifically hypertension (27% vs. 4%, p = 0.062). DISCUSSION: Healthcare workers reported mostly mild courses of COVID-19 despite increased contact with SARS-CoV-2 patients. However, some reported persistent symptoms months after infection.

Development of the "Hamburg Best Practice Guidelines for ICV-Enzyme Replacement therapy (ERT) in CLN2 Disease" Based on 6 Years Treatment Experience in 48 Patients.

Intracerebroventricular enzyme replacement therapy (ICV-ERT) for CLN2 disease represents the first approved treatment for neuronal ceroid lipofuscinosis (NCL) diseases. It is the first treatment where a recombinant lysosomal enzyme, cerliponase alfa, is administered into the lateral cerebral ventricles to reach the central nervous system, the organ affected in CLN2 disease. If untreated, CLN2 children show first symptoms such as epilepsy and language developmental delay at 2-4 years followed by rapid loss of motor and language function, vision loss, and early death. Treatment with cerliponase alfa has shown to slow the rapid neurologic decline. However, the mode of administration by 4 hour-long intracerebroventricular infusions every 14 days represents a potentially greater risk of infection compared to intravenous enzyme replacement therapies. The Hamburg NCL Specialty Clinic was the first site worldwide to perform intracerebroventricular enzyme replacement therapy in children with CLN2 disease. In order to ensure maximum patient safety, we analysed data from our center from more than 3000 intracerebroventricular enzyme replacement therapies in 48 patients over 6 years with regard to the occurrence of device-related adverse events and device infections. Since starting intracerebroventricular enzyme replacement therapy, we have also developed and continuously improved the "Hamburg Best Practice Guidelines for ICV-Enzyme Replacement Therapy (ERT) in CLN2 Disease." Results from this study showed low rates for device-related adverse events and infections with 0.27% and 0.33%, respectively. Therefore, following our internal procedural guidelines has shown to improve standardization and patient safety of intracerebroventricular enzyme replacement therapy for CLN2 disease.

Modulation of S. epidermidis-induced innate immune responses in neonatal whole blood.

BACKGROUND: Coagulase-negative staphylococci (CoNS) such as Staphylococcus epidermidis are highly prevalent pathogens for sepsis in neonates. The interaction between host, environment and pathogenic factors of S. epidermidis are still poorly understood. Our objective was to address the role of several pathogenic factors of S. epidermidis on neonatal cytokine responses and to characterize the influence of three immunomodulatory drugs. METHODS: We performed an ex-vivo model of S. epidermidis sepsis by assessment of blood cytokine production in neonatal whole blood stimulation assays (ELISA). S. epidermidis strains with different characteristics were added as full pathogen to umbilical cord blood cultures and the influence of indomethacin, ibuprofen and furosemide on neonatal immune response to S. epidermidis was evaluated (Flow cytometry). RESULTS: Stimulation with S. epidermidis sepsis strains induced higher IL-6 and IL-10 expression than stimulation with colonization strains. Biofilm formation in clinical isolates was associated with increased IL-10 but not IL-6 levels. In contrast, stimulation with mutant strains for biofilm formation and extracellular virulence factors had no major effect on cytokine expression. Notably, addition of ibuprofen or indomethacin to S. epidermidis inoculated whole blood resulted in mildly increased expression of TNF-α but not IL-6, while frusemide decreased the production of pro-inflammatory cytokines, i.e. IL-6 and IL-8. CONCLUSIONS: The virulence of sepsis strains is coherent with increased cytokine production in our whole-blood in-vitro sepsis model. Biofilm formation and expression of extracellular virulence factors had no major influence on readouts in our setting. It is important to acknowledge that several drugs used in neonatal care have immunomodulatory potential.

Incidence of infections due to third generation cephalosporin-resistant Enterobacteriaceae - a prospective multicentre cohort study in six German university hospitals.

Background: Infections caused by third generation cephalosporin-resistant Enterobacteriaceae (3GCREB) are an increasing healthcare problem. We aim to describe the 3GCREB infection incidence and compare it to prevalence upon admission. In addition, we aim to describe infections caused by 3GCREB, which are also carbapenem resistant (CRE). Methods: In 2014-2015, we performed prospective 3GCREB surveillance in clinically relevant patient specimens (screening specimens excluded). Infections counted as hospital-acquired (HAI) when the 3GCREB was detected after the third day following admission, otherwise as community-acquired infection (CAI). Results: Of 578,420 hospitalized patients under surveillance, 3367 had a 3GCREB infection (0.58%). We observed a similar 3GCREB CAI and HAI incidence (0.28 and 0.31 per 100 patients, respectively). The most frequent pathogen was 3GCR E. coli, in CAI and HAI (0.15 and 0.12 per 100 patients). We observed a CRE CAI incidence of 0.006 and a HAI incidence of 0.008 per 100 patients (0.014 per 1000 patient days). Conclusions: Comparing the known 3GCREB admission prevalence of the participating hospitals (9.5%) with the percentage of patients with a 3GCREB infection (0.58%), we conclude the prevalence of 3GCREB in university hospitals to be about 16 times higher than suggested when only patients with 3GCREB infections are considered. Moreover, we find the HAI and CAI incidence caused by CRE in Germany to be relatively low.

Comparison of Two Test Strategies for Clarification of Reactive Results for Anti-HBc in Blood Donors.

OBJECTIVE: Testing for antibodies against hepatitis B core antigen (anti-HBc) was introduced to detect blood donors suffering from occult hepatitis B infection. Confirmation of specification of reactive results in the anti-HBc screening assay is still a challenge for blood donation services. METHODS: Two different test strategies for confirmation of specification of reactive anti-HBc tests, one performed in our institute and one suggested by the German authority (Paul-Ehrlich-Institut (PEI)), were compared. The first strategy is based on one supplemental anti-HBc test, the other requires two supplemental anti-HBc tests. RESULTS: 389 samples from 242 donors were considered. Both test strategies yielded concordant results in 117 reactive samples termed 'true-positive' or 'specificity confirmed', in 156 reactive samples termed 'false-positive' or 'specificity not confirmed', and in 99 negative samples. In 17 samples obtained from 11 donors, both test strategies gave discrepant results ('false-positive' but 'specificity confirmed'). In 10 of 11 donors, a real HBV infection was very unlikely, one remained unclear. 30 donors considered 'false-positive' became negative in all anti-HBc tests after follow-up testing and thus eligible for donor re-entry. CONCLUSIONS: The test strategy suggested by the PEI yielded no additional information but induced an overestimation of HBV infections and unnecessary look-back procedures. Many anti-HBc-reactive donors can be regained after follow-up testing.

Hypertension and mild chronic kidney disease persist following severe haemolytic uraemic syndrome caused by Shiga toxin-producing Escherichia coli O104:H4 in adults.

BACKGROUND: Shiga toxin-producing, enteroaggregative Escherichia coli was responsible for the 2011 outbreak of haemolytic uraemic syndrome (HUS). The present single-centre, observational study describes the 1-year course of the disease with an emphasis on kidney function. Outcome data after 1 year are associated with treatment and patient characteristics at onset of HUS. METHODS: Patients were treated according to a standardized approach of supportive care, including a limited number of plasmapheresis. On top of this treatment, patients with severe HUS (n = 35) received eculizumab, a humanized anti-C5 monoclonal antibody inhibiting terminal complement activation. The per-protocol decision--to start or omit an extended therapy with eculizumab accompanied by azithromycin--separated the patients into two groups and marked Day 0 of the prospective study. Standardized visits assessed the patients' well-being, kidney function, neurological symptoms, haematological changes and blood pressure. RESULTS: Fifty-six patients were regularly seen during the follow-up. All patients had survived without end-stage renal disease. Young(er) age alleviated restoring kidney function after acute kidney injury even in severe HUS. After 1 year, kidney function was affected with proteinuria [26.7%; 95% confidence interval (CI) 13.8-39.6], increased serum creatinine (4.4%, CI 0.0-10.4), increased cystatin C (46.7%, CI 32.1-61.3) and reduced (<90 mL/min) estimated glomerular filtration rate (46.7%, CI 32.1-61.3). Nine of the 36 patients without previous hypertension developed de novo hypertension (25%, CI 10.9-39.1). All these patients had severe HUS. CONCLUSIONS: Although shiga toxin-producing Escherichia coli (STEC)-HUS induced by O104:H4 was a life-threatening acute disease, follow-up showed a good recovery of organ function in all patients. Whereas kidney function recovered even after longer duration of dialysis, chronic hypertension developed after severe HUS with neurological symptoms and could not be prevented by the extended therapy.

Successful treatment of extensively drug-resistant Pseudomonas aeruginosa osteomyelitis using a colistin- and tobramycin-impregnated PMMA spacer.

Discovered in 1949, the antibiotic colistin was initially used for therapeutic purposes. Parenteral use of colistin was gradually abandoned because of its side-effect profile, especially its nephrotoxicity and neurotoxicity. Despite the risk of these potentially serious adverse effects, increasing resistance of Gram-negative bacteria has led to a renaissance of intravenous use of colistin in the last few years. Local administration of colistin is an alternative method to minimise the risk of systemic toxicity. We present a case of extensively drug-resistant Pseudomonas aeruginosa osteomyelitis treated successfully with high-dose colistin- and tobramycin-impregnated bone cement as a drug delivery vehicle. For the first time, local colistin concentrations in drainage and synovial fluid were quantified in order to determine the optimal dose and to minimise serious side effects. Insertion of a bone cement spacer loaded with a high dose of tobramycin and colistin resulted in local colistin levels at the infection site that exceeded the minimum inhibitory concentration (MIC) of colistin against the isolated P. aeruginosa five-fold on Day 4. Thus, the treatment may be expected to exert a prolonged effect. Whereas systemic administration of colistin alone was not sufficient to treat the infection, combined local and parenteral therapy led to eradication of P. aeruginosa in this patient. Plasma colistin levels remained in the therapeutic range, which confirms the systemic safety of the method.

Detection of esterified cholesterol in murine Bruch's membrane wholemounts with a perfringolysin O-based cholesterol marker.

PURPOSE: To investigate the effects of Bruch's membrane (BrM) neutral lipid deposition in mouse models and its significance to aging and age-related macular degeneration, it is essential to reliably detect small quantities of neutral lipids including esterified cholesterol (EC). In chorioretinal sections and BrM wholemounts, we tested a novel fluorescent cholesterol marker based on the bacterial toxin perfringolysin O (PFO) and compared results with those obtained with the classic cholesterol dye filipin. METHODS: An engineered plasmid containing the specific cholesterol binding domain (D4) of PFO fused to green fluorescent protein (GFP) was expressed in cultured E. coli, isolated, purified, and concentrated. A total of 150 BrM-choroid wholemounts and chorioretinal sections of 11- to 13-month-old ApoE(null) mice were prepared and stained with PFO/D4-GFP or filipin for EC. Samples were examined by epifluorescence microscopy. RESULTS: The fluorescence intensity of PFO/D4-GFP was strong, stable, and, if small quantities of EC were present, superior to filipin. In all specimens, we could sharply locate the PFO/D4-GFP signal to BrM. A semiquantitative evaluation of BrM lipid deposition is possible by measuring PFO/D4-GFP fluorescence intensity. CONCLUSIONS: The use of PFO/D4-GFP allowed a robust and direct detection of EC in aged murine BrM. In wholemount samples, its strong and stable fluorescence facilitated a semiquantitative evaluation of BrM-EC content over a large area. The patterns of EC deposition in murine BrM wholemounts are comparable with findings in human BrM wholemounts. Perfringolysin O/D4-GFP could be an important tool for investigating the effects of BrM lipid deposition in mouse models.

Microevolution of the chromosomal region of acute disease antigen A (adaA) in the query (Q) fever agent Coxiella burnetii.

The acute disease antigen A (adaA) gene is believed to be associated with Coxiella burnetii strains causing acute Q fever. The detailed analysis of the adaA genomic region of 23 human- and 86 animal-derived C. burnetii isolates presented in this study reveals a much more polymorphic appearance and distribution of the adaA gene, resulting in a classification of C. burnetii strains of better differentiation than previously anticipated. Three different genomic variants of the adaA gene were identified which could be detected in isolates from acute and chronic patients, rendering the association of adaA positive strains with acute Q fever disease disputable. In addition, all adaA positive strains in humans and animals showed the occurrence of the QpH1 plasmid. All adaA positive isolates of acute human patients except one showed a distinct SNP variation at position 431, also predominant in sheep strains, which correlates well with the observation that sheep are a major source of human infection. Furthermore, the phylogenetic analysis of the adaA gene revealed three deletion events and supported the hypothesis that strain Dugway 5J108-111 might be the ancestor of all known C. burnetii strains. Based on our findings, we could confirm the QpDV group and we were able to define a new genotypic cluster. The adaA gene polymorphisms shown here improve molecular typing of Q fever, and give new insights into microevolutionary adaption processes in C. burnetii.

Lessons Learned From Outbreaks of Shiga Toxin Producing Escherichia coli.

In 2011, a large outbreak caused by a Shiga toxin producing E. coli (STEC) occurred in Northern Germany, with a satellite outbreak in Western France, including the highest number of hemolytic uremic syndrome (HUS) cases ever encountered during a STEC outbreak. The outbreak strain was characterized as an enteroaggregative E. coli of serotype O104:H4 expressing a phage-encoded Shiga toxin 2. The majority of STEC infections and HUS cases were observed in adults, with a preponderance of the female gender. The outbreak imposed huge challenges on clinicians, microbiologists, and epidemiologists but also provided important new insight for the understanding of STEC infection. Thus, novel therapeutic strategies in the treatment of HUS in adults and for decolonization of long-term STEC carriers were evaluated. This review highlights the unusual features of the recent O104:H4 outbreak and focuses on emerging new strategies in diagnostics and treatment of acute STEC-related disease, as well as STEC long-term carriage.

Association between azithromycin therapy and duration of bacterial shedding among patients with Shiga toxin-producing enteroaggregative Escherichia coli O104:H4.

CONTEXT: An outbreak of Shiga toxin-producing enteroaggregative Escherichia coli (STEC O104:H4) infection with a high incidence of hemolytic uremic syndrome (HUS) occurred in Germany in May 2011. Antibiotic treatment of STEC infection is discouraged because it might increase the risk of HUS development. However, antibiotic therapy is widely used to treat enteroaggregative E coli infection. In the German outbreak, a substantial number of patients received prophylactic azithromycin treatment as part of a therapeutic regimen with the C5 antibody eculizumab. OBJECTIVE: To analyze the duration of bacterial shedding in patients with STEC infection who did and did not receive oral azithromycin therapy. DESIGN, SETTING, AND PATIENTS: At a single center in Lübeck, Germany, 65 patients with STEC infection, including patients with HUS as well as STEC-infected outpatients without manifestation of HUS, were investigated between May 15 and July 26, 2011, and were monitored for a mean of 39.3 days after onset of clinical symptoms. MAIN OUTCOME MEASURE: Carriage of STEC after azithromycin therapy. RESULTS: Twenty-two patients received oral azithromycin and 43 patients did not receive antibiotic treatment. Among antibiotic-treated patients, long-term STEC carriage (>28 days) was observed in 1 of 22 patients (4.5%; 95% CI, 0%-13.3%) compared with 35 of 43 patients (81.4%; 95% CI, 69.8%-93.0%) who were not treated with antibiotics (P < .001). All 22 patients receiving azithromycin treatment had at least 3 STEC-negative stool specimens after the completion of treatment, and no recurrence of STEC was observed in these patients. As proof of principle, 15 patients who initially were not treated with antibiotics and were long-term STEC carriers were treated with oral azithromycin given for 3 days and subsequently had negative stool specimens. CONCLUSION: Treatment with azithromycin was associated with a lower frequency of long-term STEC O104:H4 carriage.

Regulation of biofilm formation by sigma B is a common mechanism in Staphylococcus epidermidis and is not mediated by transcriptional regulation of sarA.

Biofilm formation is a major pathogenetic factor of Staphylococcus epidermidis. In S. epidermidis the alternative sigma factor sigma B was identified to regulate biofilm formation in S. epidermidis 1457. In S. aureus sigma B dependent regulation plays a minor role, whereas sarA (Staphylococcus accessory regulator) is an essential regulator. Therefore, we investigated the impact of sigma B on sarA transcription and biofilm formation in three independent S. epidermidis isolates. Mutants with dysfunctional sigma B displayed a strongly reduced biofilm formation, whereas in mutants with constitutive sigma B activity biofilm formation was increased. Transcriptional analysis revealed that icaA transcription was down-regulated in all sigma B negative mutants while icaR transcription was up-regulated. However, transcriptional differences varied between individual strains, indicating that additional sigma B-dependent regulators are involved in biofilm expression. Interestingly, despite the presence of a sigma B promoter beside two sigma A promoters no differences, or only minor ones, were observed in sarA transcription, indicating that sigma B-dependent sarA transcript has no influence on the phenotypic changes. The data observed in independent clinical S. epidermidis isolates suggests that, in contrast to S. aureus, regulation of biofilm formation by sigma B is a general feature in S. epidermidis. Additionally, we were able to demonstrate that the sarA- dependent regulation is not involved in this regulatory pathway.

Staphylococcus epidermidis Biofilms: Functional Molecules, Relation to Virulence, and Vaccine Potential.

Medical device-associated infections, most frequently caused by Staphylococcus epidermidis and Staphylococcus aureus, are of increasing importance in modern medicine. The formation of adherent, multilayered bacterial biofilms is crucial in the pathogenesis of these infections. Polysaccharide intercellular adhesin (PIA), a homoglycan of ß-1,6-linked 2-acetamido-2-deoxy-D: -glucopyranosyl residues, of which about 15% are non-N-acetylated, is central to biofilm accumulation in staphylococci. It transpires that polysaccharides - structurally very similar to PIA - are also key to biofilm formation in a number of other organisms including the important human pathogens Escherichia coli, Aggregatibacter (Actinobacillus) actinomycetemcomitans, Yersinia pestis, and Bordetella spp. Apparently, synthesis of PIA and related polysaccharides is a general feature important for biofilm formation in diverse bacterial genera. Current knowledge about the structure and biosynthesis of PIA and related polysaccharides is reviewed. Additionally, information on their role in pathogenesis of biomaterial-related and other type of infections and the potential use of PIA and related compounds for prevention of infection is evaluated.

The role of sigmaB in persistence of Staphylococcus epidermidis foreign body infection.

Staphylococcal biofilm formation depends on the transcription factor sigma(B). We further investigated the role of sigma(B) in biofilm formation and persistence in vitro and in vivo in a subcutaneous rat model. As expected, expression of all sigma(B) operon genes was transiently higher in the first 6 h of biofilm formation compared to planktonic bacteria, concurrent with a temporary upregulation of icaA and aap expression. However, we also observed a second upregulation of sigB expression in biofilm more than 2 days old without upregulation of icaA or aap. Biofilm formation by Staphylococcus epidermidis strains 8400 and 1457 was compared to that of isogenic mutants with inactivation of rsbU, of rsbUVW and of the entire sigma(B) operon. Both wild-type strains and the constitutively sigB-expressing rsbUVW mutant showed a strong biofilm-positive phenotype. The rsbUVW mutant biofilm was, however, thinner and more evenly spread than the wild-type biofilm. Inactivation of SigB in the rsbUVWsigB mutant or mutation of the positive regulator RsbU reduced both the number of sessile bacteria and polysaccharide intercellular adhesin (PIA) synthesis. These differences between the wild-types and their respective mutants appeared after 6 h in in vitro biofilms but only after 4 days in in vivo biofilms. Our results provide additional evidence for a role for sigma(B) in biofilm formation. They also suggest a role for sigma(B) in biofilm maturation and stability that is independent of PIA or accumulation-associated protein (Aap) and point to significant differences in the temporal development between in vitro and in vivo biofilms.

Microbial interactions in Staphylococcus epidermidis biofilms.

Medical device-associated infections, most frequently caused by coagulase-negative staphylococci, especially Staphylococcus epidermidis, are of increasing importance in modern medicine. The formation of adherent, multilayered bacterial biofilms is the most important factor in the pathogenesis of these infections, which regularly fail to respond to appropriate antimicrobial therapy. Progress in elucidating the factors functional in elaboration of S. epidermidis biofilms and the regulation of their expression with a special emphasis on the role of quorum sensing are reviewed. Significant progress has been made in recent years, which provides the rationale for developing better preventive, therapeutic and diagnostic measures.